From changing our minds about preventive care and changing policies on food to halting outbreaks of infectious diseases and harnessing a biotechnology that’s the stuff of science fiction, the year 2015 provided plenty of significant news in the world of public and personal health. Here are the most compelling and controversial health stories of the year.

Measles Returns to the U.S.

A measles outbreak earlier this year in Orange County, California prompted the state to pass a law that does not permit vaccine exemption for either religious or philosophical reasons. REUTERS/Brian Snyder

At the start of the year, parents were petrified by the growing measles outbreak that began in California’s Orange County, and then spread to a number of states including Massachusetts, New Jersey, New York, Nevada, South Dakota, Texas and Utah. Health officials determined the outbreak began at Disneyland during the busy holiday season when 40 people—most unvaccinated—visited the amusement park. From the start of 2015 until the new year, there were 173 diagnosed cases of measles in 21 states and the District of Columbia, according to the U.S. Centers for Disease Control and Prevention (CDC). In June, California became one of a number of states to pass a law that prevents parents from seeking vaccine exemption on the basis of philosophical and religious beliefs. California, West Virginia and Mississippi are currently the only three states in the U.S. that don’t allow vaccine exemption for either religious or philosophical reasons. However, most states still allow exemption to families who observe religions that don’t permit immunization. The antivaxxer community continues to argue that vaccines are unsafe. Additionally, critics say legal measures enforced by the state infringe upon personal liberties and the choice should remain in the hands a child’s parents or caregiver.

Ebola began to spread through multiple countries in West Africa in February 2014, and continued through 2015. The region struggled to contain the virus, and afterward, the World Health Organization was criticized in a scathing report from the Harvard Global Health Institute and the London School of Hygiene & Tropical Medicine for its response to the outbreak. The report, published in the Lancet, outlines recommendations for how the agency—and the world—should handle future outbreaks. Along with a number of proposed guidelines, the report suggests that the WHO should no longer take on a leadership role in handling future outbreaks of Ebola.

Executives of the company have used the outbreaks of food poisoning to reinforce that they serve food of exceptional quality—so fresh that it could make you ill. The 2014 shareholder report points this out: “We may be at a higher risk for foodborne illness outbreaks than some competitors due to our use of fresh produce and meats rather than frozen, and our reliance on employees cooking with traditional methods rather than automation.” But what this really means is that the company may not be properly training employees on food preparation safety.

Raising the Meat Stakes

The World Health Organization added bacon and other processed meats to its list of carcinogens. REUTERS/Rick Wilking

Officials from the WHO weren’t the only ones with a vendetta against the standard Western diet. This year, the Dietary Guidelines Advisory Committee, a panel supported by the U.S. Department of Health and Human Services and the U.S. Department of Agriculture, proposed new U.S. dietary guidelines. This guidance—updated every five years—is meant to provide reliable and accurate information on what to eat based on the latest nutrition and food science. In the report, the panel said an increasing body of research suggests a plant-based diet—especially low in red meat and sugar—is better for humans and the environment.

Republican lawmakers argued the panel relied on less-than-relevant science to back up the proposed guidelines, and some politicians proposed bills that would create restrictions on which research can be used to write dietary guidelines. Additionally, a paper published in BMJ argued that the panel included outdated and poorly designed studies for the report, and in some cases skipped over significant research. The HHS is set to release final guidelines at the end of the month.

Breast Screen Time

The American Cancer Society published new guidelines for breast cancer screening with mammography, recommending women begin the annual test later in life. REUTERS/Eric Gaillard

The American Cancer Society (ACS) updated its breast cancer screening guidelines for the first time in more than 10 years. Up until 2015, the ACS recommended women undergo breast cancer screening with mammography starting at age 40, but the organization now suggests women start annual screening at age 45 and shift to biennial screening at 55. Women’s health advocates and physicians argued that the new guidelines are not sufficient for reducing mortality rates for the disease. Some critics also say the ACS guidelines are too complicated for the public to accurately understand. In response, members of women’s health care organizations will convene a meeting to discuss creating uniform guidelines and reach some consensus.

Under Blood Pressure

The National Institutes of Health released preliminary results of a landmark trial on treating high blood pressure through earlier and more aggressive intervention with medication. The Systolic Blood Pressure Intervention Trial (SPRINT) found medicating patients to achieve a blood pressure reading of 120 millimeter of mercury (mm Hg) reduced risk for heart failure and stroke by 25 percent and overall mortality by as much as 27 percent. There was also a 43 percent reduction in death from heart-related events for patients 50 and over who hit 120 mmHg. These findings were so notable that the NIH stopped the trial early to ensure that patients in the control group received the right doses of medication. Some critics in the medical field said they believed the NIH acted prematurely in the decision to end the trial early. Editors of the New England Journal of Medicine stated the findings of the trial signaled better treatment for high blood pressure “is a public health urgency, not an emergency.”

Safer Sex

A number of significant studies published this year showed pre-exposure prophylaxis (PrEP) is highly effective for preventing the transmission of the HIV virus. When taken daily, the antiretroviral pill—known as Truvada—reduces the risk for HIV transmission by more than 90 percent for men who have sex with men and more than 70 percent for people who inject drugs. This growing body of research around the effectiveness of PrEP prompted the CDC to publish national estimates of the number of patients who should be counseled by health care providers about PrEP. Some people have argued prescribing PrEP promotes unsafe sex practices, such as having unprotected sex with multiple partners. Some studies on PrEP observed HIV transmission drastically plummeted but rates of of sexually transmitted infections on the whole were still significantly high.

In September, Martin Shkreli’s company Turing Pharmaceuticals was accused of price-gouging a life-saving drug: Turing purchased the rights to the decades-old drug and raised its cost from $13.50 a pill to $750. The news prompted Democratic presidential candidate Hillary Clinton to urge U.S. regulators to determine how to bring lower-cost generic drugs to the market, citing the "egregious actions of Turing Pharmaceuticals." Since at least January, Shkreli has also been under a criminal investigation by the U.S. Attorney General in connection to Retrophin, a public company founded by Shkreli in 2011. In December, officials arrested Shkreli on fraud charges and he could face up to 20 years in prison.

Twice Rejected, Once Approved

After months of speculation, the Food and Drug Administration in August signed off on Addyi (flibanserin), a prescription to treat low sexual libido in women. The agency’s decision was criticized since the drug, produced by Sprout Pharmaceuticals, has been found to cause a number of serious side effects, including nausea, dizziness and fainting when combined with other drugs or alcohol. Many critics also argued that it was not effective enough; women taking part in trials reported an average of two to three more satisfying sexual events per month. The drug, twice rejected for approval before, hit the market in October.

Talented Video Editing

Lawmakers in several states made attempts to defund Planned Parenthood after a sting operation by the Center for Medical Progress accused the organization of selling “baby parts.” REUTERS/Mike Blake

Over the summer, the Center for Medical Progress launched a smear campaign accusing Planned Parenthood of selling “baby parts” through its fetal tissue donation program. Planned Parenthood in turn accused the group of deceptively editing the videos to make it appear that the organization receives financial compensation. In the wake of the campaign, federal and state lawmakers throughout the country tried to defund the organization, and the National Abortion Federation sued the Center for Medical Progress on the grounds that the group of “citizen journalists” in the anti-abortion group infiltrated its meetings by lying about their identities.

Burnt to a CRISPR

In early December, scientists met in Washington, D.C. for the International Summit on Human Gene Editing to discuss CRISPR-Cas9, an affordable, effective—and highly controversial—technology created in 2012 that provides a way to edit the DNA of any living organism. Researchers so far have utilized CRISPR to make mosquitoes resistant to malaria, grow better produce and alter the pig genome in ways that could make the animal’s organs fit for transplantation to humans. This year, researchers in China also published a study in which they used CRISPR to alter a human embryo, an accomplishment some scientists and lawmakers fear should be stopped promptly. Perhaps 2016 will be the year of designer babies?